1. Field of the Invention
The present invention relates generally to methods and devices for performing multiple, sequential intraluminal procedures. In particular, the method and apparatus utilize two or more interactive devices, including therapeutic and diagnostic devices, on separate catheters by selectively positioning at least one of the devices at a desired target site within the lumen while the other device(s) remain close by for subsequent use.
In percutaneous transluminal angioplasty procedures, a catheter having an expandable distal end, usually in the form of a balloon, is positioned in a lumen of a blood vessel with the distal end disposed within a stenotic atherosclerotic region of the vessel. The expandable end is then expanded to dilate the vessel and, upon withdrawal, restores adequate blood flow through the diseased region. During dilatation, blood flow is interrupted, limiting inflation time to between 0.5 and 3 minutes.
While angioplasty has gained wide acceptance, it continues to be limited by two major problems, abrupt closure and restenosis. Abrupt closure refers to the acute occlusion of a vessel immediately after or within the initial hours following the dilatation procedure. This complication occurs in approximately one of twenty cases and frequently results in myocardial infarction and death if blood flow is not quickly restored. At present, arterial dissections are treated by prolonged balloon inflations lasting more than 5 minutes. Special angioplasty balloon catheters which allow for perfusion through the dilatation catheter during inflation are usually necessary for such prolonged procedure.
Restenosis refers to the re-narrowing of an artery after an initially successful angioplasty. Occurring usually within the initial six months after angioplasty, restenosis afflicts approximately one in three cases. That is, approximately one in three patients will require additional revascularization procedures. Many different strategies have been tried unsuccessfully to reduce the restenosis rate, including mechanical (e.g., prolonged balloon inflations, atherectomy, laser and stenting) and pharmacologic (e.g., calcium antagonists, ace inhibitors, fish oils, steroids and anti-metabolic) approaches. A promising new strategy is to deliver agent directly to the arterial wall at the site of angioplasty. Several devices have been developed to deliver agent locally into the arterial wall. Similar to angioplasty balloon catheters, most drug delivery catheters interrupt blood flow, limiting the duration of time to deliver agent. Another promising strategy is to use intravascular ultrasonic imaging to guide the initial revascularization (e.g. balloon angioplasty, atherectomy, etc . . . ).
Presently the use of multiple modalities to treat a single lesion requires different catheters. In clinical practice, this means that one catheter must be removed while maintaining guide wire position after which the second catheter is tracked over the guide wire to the site of interest. The maneuver, commonly referred to as an "exchange" adds time to the procedure, increases blood loss and jeopardizes maintenance of the guide wire position.
For these reasons, it would be desirable to provide improved methods and devices for performing multiple, sequential intraluminal diagnostic and/or interventional procedures. It would be particularly desirable if such methods and devices permitted the introduction of a single catheter system employing discrete catheter components, each of which would have at least one diagnostic or interventional capability, in such a way that the components can be interchanged within the system. More particularly, it would be desirable to provide catheter components or elements having one or more diagnostic and/or interventional capabilities, where the components could be utilized in conjunction with conventional interventional and imaging catheters. Even more particularly, it would be desirable if such catheter components could provide for imaging, drug delivery, blood flow perfusion, pretreatment (e.g., slitting) of arterial plaque, and the like. All such catheters, catheter systems, and methods, should provide for rapid redeployment of each of the individual diagnostic, imaging, and interventional capabilities so that the proper treatment, diagnosis, or imaging can be performed at any point during a procedure without unnecessary delay.
2. Description of the Background Art
U.S. Pat. No. 4,976,689, describes an exchange catheter which is carried on a balloon catheter and which may include perfusion ports for maintaining blood flow through stenosed regions of the blood vessel. Other catheter perfusion systems are described in U.S. Pat. Nos. 4,661,094; 4,790,315; 5,009,636; 5,087,247; 5,163,921; and 5,180,364. U.S. Pat. Nos. 5,219,335 and 5,203,338 describe vascular catheters having reduced diameter distal ends. The '335 patents shows a dilatation balloon formed on the distal end. Catheters combining ultrasonic imaging and balloon dilatation are described in U.S. Pat. Nos. 4,841,977; 4,917,097; and 5,117,831. A catheter combining laser ablation and ultrasonic imaging is described in U.S. Pat. No. 4,576,177. A variety of intraluminal ultrasound devices is described in Bom et al. (1989) Int. J. Cardiac Imagining 4:79-88. Phased-array ultrasound imaging catheters are commercially available from EndoSonics, Pleasanton, Calif., as described in a brochure entitled The Cathscanner.RTM. Intracoronary Imaging System. Balloon-tipped catheters appropriate for angioplasty treatment procedures are described in, for example, U.S. Pat. No. 5,041,089, U.S. Pat. No. 4,323,071, U.S. Pat. No. 4,292,974, U.S. Pat. No. 4,762,129, and U.S. Pat. No. 4,775,371. A catheter for locally applying medication to the wall of a blood vessel or other lumen is described in U.S. Pat. No. 5,087,247, the catheter having a balloon near its distal end which is expanded with a medication, which then flows through minute holes in the balloon surface at a low flow rate. U.S. Pat. No. 4,994,033 describes an intravascular drug delivery catheter having a pair of expansion members concentrically arranged near its distal end wherein an agent is delivered to the outer expansion member, after which the inner expansion member is expanded, thereby expanding the outer member against the vessel wall and forcing the agent through minute holes in the outer member to bathe the vessel wall. U.S. Pat. No. 5,021,044 describes an intravascular drug delivery catheter having a plurality of holes on the outer surface of the catheter body through which an agent may be delivered to a site within a vessel. U.S. Pat. No. 5,112,305 describes a catheter for delivery of therapeutic agents to an interior wall of a vessel, the catheter having a balloon near its distal end with tubular extensions capable of projecting from its outer surface. An agent is delivered to the balloon which both expands the balloon and flows through the tubular extensions into the vessel wall. Other drug delivery devices are described in U.S. Pat. No. 4,693,243, U.S. Pat. No. 4,406,656, U.S. Pat. No. 5,015,232, and U.S. Pat. No. 4,850,969. An inflatable percutaneous oxygenator having a network of gas permeable fibers for oxygenating blood is described in U.S. Pat. No. 5,219,326. U.S. Pat. No. 4,766,337, describes a radially expandable vascular stent. U.S. Pat. No. 5,092,877, describes a self-expanding vascular stent which is carried in a sheath over an angioplasty balloon catheter.